Sounds like you might have entered the IRA distribution twice, once without treating it as a qualified disaster distribution and the other as a qualified disaster distribution that you chose to treat as taxable over three years. Only the one entered as a qualified disaster distribution will be reported on Form 8915B. Go back to the Form 1099-R entry section and check for a double entry of the distribution.
Also be aware that the amount on Form 1040 line 4a will be the total amount of IRA distributions in 2018, including any amounts rolled over and the entire amount of the qualified disaster distribution. Line 4b will show the taxable amount which, in the absence of any other taxable distributions will be the taxable amount determined on Form 8915B.
